This invention relates to terpenoids and more particularly to monoterpenoids and sesquiterpenoids from biorational sources for use as repellents against arthropods.
The use of insect repellents is widely accepted throughout the world. Besides repellents intended for outdoor use, repellents are also available for use in homes to repel pests such as cockroaches, termites, ants, fleas, and so forth. The commercial standard for insect repellency is N,N-diethyl-3-methylbenzamide (DEET). The U.S. Environmental Protection Agency (EPA) estimates that more than 38% of the U.S. population uses a DEET-based insect repellent every year and that worldwide use exceeds 200,000,000 people annually (U.S. Environmental Protection Agency, PBS1-207722, 1980). However, DEET is known to cause severe adverse health effects in some people, particularly in higher concentrations. (See, for example, Qui et. al., 1998, J. Am. Mosq. Control Assoc. 14 (1):12-27; Miller, J. D., 1982, New Eng. J. Med. 307:1341-1342; Roland, et. al., 1985, Can. J. Med. Assn. J. 132:155-156).
Citronella is a biorational repellent that is also widely used. Although citronella poses less health risks than other, more toxic repellents, citronella is known to be highly volatile. As a result, any activity that might be present is lost rather quickly. In particular, citronella candles have been shown to be marginally effective, if at all.
Very little is known about the mechanisms involved in repelling many target pests such as cockroaches. It is also not known whether there are inherent differences between the ability of a male to detect a repellent as compared with a female of the same species.
What is needed, therefore, are new types of effective biorational repellents to replace commercial products that are toxic. The replacement repellents need to be economical, highly repellent to target pests, and pose less actual risk to the environment and humans as compared to traditional repellents.
A repellent composition comprising an amount of a monoterpenoid or sesquiterpenoid effective to repel a target pest from a target area, the monoterpenoid or sesquiterpenoid in combination with a carrier is disclosed. In one embodiment, the monoterpenoid or sesquiterpenoid is from a biorational source, such as a plant volatile. In a particular embodiment, the plant volatile is a monoterpenoid, such as xe2x80x9cnepetalactonexe2x80x9d (or the individual nepetalactone isomers) derived from catnip (Nepeta cataria). In another embodiment, the plant volatile is any one or a combination of sesquiterpenoids derived from the fruit of the Osage orange tree (Maclura pomifera). Such compositions have repellency against arthropods, such as cockroaches, mosquitoes, mites, ticks, spiders, and so forth.
A method of repelling a target pest from a target area comprises applying an effective amount of a composition comprising the compound together with a suitable carrier in or near a target area, including applying the composition directly onto humans, animals (e.g., pets, livestock), and so forth. Repellents can also be applied to other target areas, including, but not limited to, plants, articles of clothing, tents, sleeping bags, pillows, bed nets, blankets, premises, etc.
It has also been determined that the chemoreceptors responsible for repellent response are present on the antennae of the German cockroach. Such chemoreceptors are likely present on the antennae of other arthropods as well. It has also been determined that male cockroaches are generally more sensitive to odors than female cockroaches.